Froth flotation of acidic minerals



Patented Dec. 7, 1943 ururso 'Trss PATENT more r'Lo'rA'Hon F ACIDICMINERALS Stephen Edward Erickson, Springdale, Conn, as-

signor to American Cyamamid Company, New York, N. it, a corporation ofMaine No Drawing. Application September 13, 1940, Serial No 356,651

7 Claims.

are subjected to a separation or concentration process in the presenceof a promoter, said promoter being the condensation products obtained byreacting a monoalkylol cyanamide 01" polymerized monoalkylol cyanamidewith a primary or secondary aliphatic amine to effect separation of theacidic minerals from the other ore constituents. Particularly thisinvention relates to the use of the reaction products of monoalkylolcyanamides with aliphatic amines, either as the free base or as thesubstantially water soluble salt of such .a product, as promoters foracidic minerals in froth flotation, film flotation, stratiflcation,agglomeration, tabling and related mineral separation processes. Whilethe invention is not limited to any particular ore concentrating processor to any particular ore, its most important held of usefulness is inconnection with the froth flotation processes of separating silica orsilicate minerals, such as mica, from non-metallic ores, such aslimestone, bauxite, barytes, 'ilmenite, calcite and the like, andespecially phosphate minerals.

i'he compounds that have been found to have a selective filmingattraction for acidic ore materials and which are useful for carryingout this invention include broadly the cond sation proddots ofmonoalkylol cyanamides Oi. polymerized able by heat and accordingly whenheated they will form as an intermediate a polymerization product. Inthis invention, therefore, his intended that the term monoalkylolcyanamide as used hereinafter in both the specification and the claimsshall include both the unpolymerized monoalkylol cyanamide and the dimerthereof when present, unless provision therefor has otherwise been madetherein.

The monoalkylol cyanamides described above may be condensed with eithera primary allphatic amine or a secondary aliphatic amine to produceproducts which have an aflinity for and will act as promoters orcollectors for acidic ore materials.

A suitable method for producing the condensation products describedabove comprises heating together a primary or secondary amine with amonoalkylol cyanamide in an acid medium.

monoalkyiol cyanamide with a primary or sec- 7 ondary aliphatic amine.

The monoalkylol cyanamides are compounds which may be produced byreacting an aqueous.

slurry of calcium cyanamide, a solution of sodium cyanamide or otheralkali or alkaline earth metal salt of cyanamide with one or more mols.of an alkylene oxide, such as ethylene oxide, propylene oxide, etc. Forexample monoethylol cyanamide may be produced by treating an aqueousslurry of calcium cyanamide at temperatures below 25 C. with a solutionof sodium hydroxide.

The mixture is then filtered to remove the insolubles and the sodiumcyanamide produced remains in the solution. Slightly less than thetheoretical quantity of ethylene oxide at a temperature not exceeding 10(2. is then added to the aqueous slurry of the calcium cyanamide whilestirring and the cold mixture allowed to stand for about 24 hours. Themonoalkylol cyanamide in the mixture is then extracted with portions ofchloroform followed by evaporation of the chloroiorm from the extractunder reduced pressure to recover the product.

The monoalkylol cyanamides are polymeriz- While the heating of thecomponents may be carried out in any manner found suitable, preferablyan acid should be present in order to effect the condensation. Goodresults have been obtained with acids, such as hydrochloric, sulfuric,acetic, or similar acids which were present either in the free state orin the form which such an acid takes when it has been combined with anorganic base to form a salt therewith.

In accordance with the above method suitable condensation products havebeen prepared by heating together monoetl'iylol cyanamide hydrochloridewith butylamine; monoethylol cyanamide acetate with dodecylamine;monolsopropylol cyanamide hydrochloride with dodecylarnine andmonoisopropylol cyanamide with dodecylamine hydrochloride;monoethylolcyanamide with dl-n-propyl amine, hydrochloric acid having inpart dispersible therein and which can be made.

soluble in water bythe addition of an acid such as hydrochloric oracetic acid.

- The promoter action otthe reagents of the present inventionwill, ofcourse, vary with dit-' ierent ore minerals and with the difierentmonoalkylol cyanamide amine condensation products or salts used. It isan advantage of the invention, however, that good results are obtainedwhen the compounds are used in the form of their water soluble salts,for example, the acetates. However, it is not necessary to use the watersoluble salts, and the compound in the form of the free base may be usedprovided satisfac tory dispersion and distribution are effected. In

economically concentrated by using these reagents in conjunction withother materials such as fuel oil or pine oil and ubjecting toconcentration by the use of tables or by film flotation.

froth flotation operations dispersion may be ef- 5 The 28 mesh phosphaterock material is best fectively obtained by feeding an alcoholicsoluconcentrated by means of froth flotation emtion of the compound intothe flotation circuit ploying these improved silica promoters.

or by the use of emulsions containing the reagent When the reagents ofthe present invention are dispersed therein. employed as promoters inthe froth flotation of The reagents of the present invention are effecl0silica from phosph e r th conditions y be tive promoters or collectingagents for acidic varied in accordance with procedures known to orematerials generally and said acidic materials those skilled in the art.The reagent may be may be either worthless gangue or valuable oreemployed in theform of aqueou solutions, emulconstituents. The mostimportant use, however, sions, mixtures, or solutions in organicsolvents is in connection with the froth flotation of silica such asalcohol and the like. The reagents may from non-metallic ores in whichthe siliceous be'introduced into the ore pulp in the flotation ganguemay represent a much smaller proportion cell without prior conditioningor they may be of the ore, rather than metallic and sulfide oresconditioned with the ore pulp prior to the actual in which the gangueusually represents the major concentration operation. They may also bestage proportion of the ore. Representative acidic ore fed into theflotation circuit. materials are the feldspars, quartz, pyroxenes, Otherimproved phosphate flotation features the spinels, biotite, muscovite,clays, and the like. which are known may be utilized in connection Whileas stated heretofore the present inwith the present invention such asthe very comvention is not limited to the treatment of any plete removalof the slimes prior to flotation which particular ore materials, it hasbeen found to be is an aid to better results as pointed out in the wellsuited for froth flotation of silica from phos- Erickson application,Serial No. 325,011, filed phate rock, and this is a preferred embodimentMarch 20, 1940, and the Mead and Maust appliof the invention. In theprocesses of removing cation, Serial No. 320,121, filed February 21,1940, silica from phosphate rock the conditions are which describes aprocess for classifying and desuch that practically complete removal ofthe sliming phosphate flotation feed by means of a silica must beaccomplished in order to produce hindered settling classifier and whichdeslimed a salable phosphate material. It is therefore an feed is wellsuited for treatment in accordance advantage of this invention that ourreagents not with this invention. only effect satisfactory removal of thsilica but The invention will be further illustrated by the areeconomical in amounts used. The quantities following specific exampleswhich are illustrarequired range from 0.1 pound to 2.0 pounds per tionsof the preferred embodiments thereof, but ton of ore depending upon theparticular ore and it is not intended to limit the invention thereby.the particular reagent. Th invention i not, Example I however, limitedto the use of such quantities.

These reagents have also been successfully used Flotation tests asfollows were made 011 a for the flotation of feldspar from quartz andfor sample of Florida phosp e om t e 1d the flotation of mica fromquartz and calcite. Colony mine near Brewsters Ore ateria Th reagent ofthe present invention may b which was essentially 48 +200 mesh materialused alone or in mixtures with other promoters. was agitated and s ru dwith w ter to break They may likewise be used in conjunction with up theclay balls. The slimes were subseque t y other cooperating materialssuch as conditionremoved by de an ation and repeated washing ingreagents, activators, frothing reagents, deun t Ore material aSubstantially f e o pressing reagents, dispersing reagents, oilymaslimes. terials such as hydrocarbon oils, fatty acids or Sep ra e 600gram samplesof deslimed flotafatty acid esters, tion feed were dilutedto 22%; solids with water These new reagents are also adaptable for useand transferred to a labor tory size Fa r n in any of the ordinaryconcentrating processes flotation machine. The particular reagent orresuch as fllm flotation, tabling, and particularly agent combinationwas then added and condiin froth flotation operations. The oreconcentioned with the pulp for 3 seconds. Air was adtrating processesemployed will depend upon the mitted to the machine and the resultantconcen. particular type or kind of ore which is being trate was skimmedoff for 2 minutes. The flotaprocessed. For example, in connection withphosv tion test prod Wer hen fil e d, phate rock, relatively coarse,phosphate-bearing weighed, and assayed. The metallurgical data material,for example 28 mesh or larger, canbe obtainedin these tests arepresented in'Table I.

Table I Concentrate Telling mt Fe R u LbsJton n Dist. mu. m ofleod W at?has. aar teas. e,

' Condensation product of cthanolcyannmido 5.92 55.04 03.42 93.40 44.06-54 3 12% god ylamine acetate 3.3 lGondanliii'rififiid'u't'tl'iiiiiiibic msm 'i' 56,23 57,00 92.80 95.112.3 3 gl godecylamlneacetnte---. gig

oondenit'fiifi'gkiic"iioiyifiififiifi a"-.- 50.00 54.03 05.14 91.8045.90 9.96 8.20 og ysmmi canddodecylumlneaootntmg3 While the aboveexamples relate specifically to the flotation of silica from phosphaterock, the present invention is not limited to such operations and thereagents are useful in the treatment of various other types of orematerials wherein it is desirable to remove acidic minerals in thefroth. For example, the reagents are useful in the treatment of thecoarse portion of the tailingsproduced in cement plant flotationoperations. In this particular instance the rake sands are treated byflotation to remove part of the alumina which is present in the form ofmica and the removal of silica is not desirable. Our reagents have beenfound to be useful in such flotation operations. The reagents may alsobe, used for the flotation of silica from iron ores containingmagnetite, limonite and quartz, vand in tests conducted on this type ofore the rough tailing resulting from the flotation of silica containingboth magnetite and limonite, assayed much higher in iron thanconcentrates produced by the conventional soap flotation of the ironWhat I claim is: I

1. In a process of separating acidic ore materials from non-metallic oreconstituents the step comprising subjecting the ore in an aqueous pulpto a concentrating operation in the presence of a reagent selected fromthe class consisting of the condensation products of aliphatic primaryamines with the reaction product of an alkylene oxide and a substance ofthe group consisting of alkali metal and alkaline earth metal salts ofcyanamide, and salts of such products.

2. In a process of separating acidic siliceous gangue from phosphate orevalues the step comprising subjecting the ore in an aqueous pulp to aconcentrating operation in' the presence of a reagent selected from theclass consisting of the condensation products of aliphatic primaryamines with the reaction product of an alkylene oxide and a substance cfthe group consisting of alkali metal and alkaline earth metal salts ofcyanamide, and salts of S'l-ICh PIOdUCtS.

3. In the froth flotation process of separating non-metallic ore valuesfrom acidic siliceous gangue the step which comprises subjecting the oreto'a iroth flotation in the presence of a reagent chosen from the'groupconsisting of the condensation products of aliphatic primary amines withthe reaction product of an alkylene oxide and a substance of the groupconsisting of alkali metal and alkaline earth metal salts of cyanamide,and salts of such products.

4. In the froth flotation process of separating phosphate ore valuesfrom acidic siliceous gangue the step which comprises subjecting the oreto a froth flotation in the presence of a reagent chosen oxide andcalcium cyanamide.

6. In the froth flotation process of separating phosphate ore valuesfrom acidic siliceous gangue the step which comprises subjecting the oreto froth flotation in the presence of a promoter comprising thecondensation product of dodecylamine with the reaction product ofethylene oxide and calcium cyanamide. v

'7. In a process of separating acidic ore materials from non-metallicore constituents the step comprisingpsubjecting the ore in an aqueouspulp to a concentrating operation in the presence of a reagent selectedfrom the class consisting ofthe condensation products of aliphaticprimary amines with the reaction product of an alkylene oxide and asubstance of the group consisting of alkali metal and alkaline earthmetal salts of cyanamide, the condensation products of aliphaticsecondary amines with the reaction product of an alkylene oxide and asubstance of the group consisting of alkali metal andalkaline earthmetal salts of cyanamide, and salts of such products.

STEPHEN EDWARD ERICKSON.

